Self-contained motor driven hydraulic supply unit

ABSTRACT

A compact hydraulic supply unit has a housing forming a reservoir for a pressure fluid, and includes a housing bottom, a housing cover and a housing middle part therebetween in the form of a profiled tube. An electric motor has a laminated stator core held by the housing middle part, and drives a pump located at the housing bottom. The housing middle part has axially extending internal holding Webs for holding the laminated stator core. The size of the housing middle part is independent of the size of the electric motor, so that, with a low structural height, the housing can be so formed that it accepts a larger volume of pressure fluid.

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to a compact hydraulic aggregate which possesses ahousing forming a reservoir for a pressure fluid, which comprises ahousing bottom, a housing cover and a housing middle part therebetweenin the form of a profiled tube, an electric motor located in the housingwhose in stator laminated core is held by the housing middle part andwhich can be connected to an electricity network via a connection box onthe housing cover, and a pump located within the housing in the regionof the housing bottom and capable of being driven by the electric motor.

Such a compact hydraulic aggregate is known, for example, from DE 35 13472 C2. In such a hydraulic aggregate, the housing may also be regardedas the housing of the electric motor. The rotor and stator of theelectric motor are more or less deeply immersed into the pressure fluid,depending on how much oil has been introduced into the reservoir and howmuch pressure fluid is specifically received by the hydraulic user orusers which are supplied with pressure fluid by the pump. The heatgenerated by the electric motor and the heat introduced into thereservoir by the pressure fluid is released to the environment via thehousing. In some circumstances, the pressure fluid, when flowing backfrom the hydraulic user, additionally passes through an oil cooler inorder to reduce the input of heat into the reservoir. This oil coolermay be directly affixed to the hydraulic aggregate.

The housing middle part of the known hydraulic aggregate is of circularcross-sectional form internally in the region of the stator laminatedcore of the electric motor. An exchange of pressure fluid between thespaces in front of the two end faces of the stator laminated core isevidently to take place via channels in the stator laminated core.

In the known compact hydraulic aggregate, the internal diameter of thehousing middle part is determined by the external diameter of the statorlaminated core, so that, for a given stock of pressure fluid, aparticular height of the hydraulic aggregate results, whereby theplacement of the hydraulic aggregate adjacent to a machine is sometimesprevented. In addition, the flow cross section is small because of thechannels of the stator laminated core accepting the coils. In somecircumstances, additional longitudinal channels have to be made in thestator laminated core, which results in an electric motor of specialdesign.

SUMMARY OF THE INVENTION

It is an object of the present invention further to develop a compacthydraulic aggregate having the features of the introductory-mentionedparagraph in such a manner that, especially if additional members arebuilt on, it can be produced cost-effectively. In addition, a lowstructural length is to be possible for a given pressure fluid storagevolume.

This object is achieved, according to the invention, in that a compacthydraulic aggregate having the introductory-mentioned features isadditionally equipped with features wherein holding webs make theexternal diameter of the stator laminated core and the internal diameterof the housing middle part independent of one another, as it were, andthe housing middle part can be formed independently of the size of theelectric motor to suit the desired storage volume of the pressure fluidand in the interests of a small structural length of the hydraulicaggregate. There is a great deal of free space between the holding websfor the completely unobstructed exchange of pressure fluid between thetwo spaces in front of the end faces of the stator laminated core. Theheat generated in the electric motor is guided outward via the holdingwebs and released to the environment via the outer surface of thehousing middle part.

Particularly preferably, the housing middle part has the external shapeof a polygon, in particular a regular polygon. In this arrangement, apartial surface between two corners should lie diametrally opposite afurther partial surface, so that the housing middle part can be wellclamped for machining. In addition, a component which is externallyangular can be stacked better than a circular component. The holdingwebs advantageously each extend at the center of an external partialsurface of the housing middle part lying between two corners, so thatthe accumulation of material in the corners does not become too great.

An embodiment of the invention is also particularly preferred whereinthe housing middle part comprises a further axially extending internalweb between two holding webs for the stator laminated core of theelectric motor, which further web is broader in the circumferentialdirection of the housing middle part than the holding webs and serves tosecure a monitoring member located externally on the housing. Forexample, threaded holes can be drilled in the further web to permit theattachment of an oil level display glass.

This further holding web is also preferably located at the center of anexternal partial surface of the polygonal housing middle part, so that alevel installation surface for the monitoring member is providedexternally.

As has already been indicated, the compact hydraulic aggregate canadditionally be equipped with an oil cooler which is disposed in theregion of the housing bottom, for example even below the housing bottom.Preferably, the fan wheel of this oil cooler is driven by a furtherelectric motor, so that no shaft need be guided out from the housingforming the reservoir. According to a feature of the invention provisionis now made, in an advantageous manner, for the supply cable for theelectric motor to be guided in an axially extending cable duct of thehousing middle part to the housing cover, and especially into theconnection box there. The supply cable is thus largely protected againstdamage. In particular, the cable duct also extends within the housingbottom and the housing cover, so that the cable is not visible at allfrom outside.

A temperature sensor, which can be used, for example, for switching anexisting oil cooler on and off or, if no oil cooler is present, switchesoff the electric motor driving the pump is advantageously disposed inaccordance with other features of the invention wherein the electricalconnection line of the temperature sensor thus extends freely neitherinside nor outside the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of embodiment of a compact hydraulic aggregate according tothe invention is illustrated in the drawing. The invention will now beexplained in detail with reference to the figures of this drawing.

In the figures:

FIG. 1 shows a longitudinal section through the example of embodimentequipped with an oil cooler, an oil level display glass and atemperature sensor, and

FIG. 2 shows a section through the housing middle part alone, along theline II—II in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The compact hydraulic aggregate shown possesses a housing 10, which onthe one hand performs the function of the reservoir for the pressurefluid used for operation and in addition can also be regarded as ahousing of an electric motor. This housing has, as essential parts, ahousing cover 11, a housing bottom 12 and a housing middle part 13. Thelatter is a section of a profiled pipe produced from an aluminum alloyand has been finally machined. The outside of the housing middle part 13is formed as a regular sixteen-sided figure with individual partialsurfaces 14 between two corners. On the inside of the peripheral wall ofthe housing middle part 13, a total of twelve holding webs 15 En extendtoward the axis 16 of the housing middle part 13. These holding webs aregrouped in four sets of three holding webs each, the three holding webs15 of each group being located at the centers of three consecutive outerpartial surfaces 14. Between the four sets of holding webs 15 is, ineach case, an outer partial surface 14 on which no holding web 15 ispresent internally. The holding webs 15 are hollowed out over aparticular axial distance from one end face of the housing middle part13, so that, on each holding web 15, a radially inward-pointing partialsurface 17 in the shape of a regular cylinder, lying on a regularcylinder with the corresponding partial surfaces 17 of the other holdingwebs 15, and an axial bearing shoulder 18 are formed. From one side, thestator laminated core 19 and the stator of an electrical motor 21,having the coils 20, are pushed into the housing middle part 13 withpressure fit as far as the bearing shoulder 18.

Inwardly and at the center of one of the partial surfaces 14 between twosets of holding webs 15, the housing part 13 is provided with a furtherweb 25 extending in the longitudinal direction, this further web 25extending less far radially inward than the holding webs 15 and beingthicker than the holding webs 15 in the circumferential direction of thehousing middle part 13. In the region of the holding web 25, two holes26 are drilled opposite one another in the axial direction into thehousing middle part 13 and have been provided with a thread. As a resultof the web 25, the holes 26 have become long enough to serve for theattachment of an oil level display glass 27 by means of two screws 28.The hydraulic aggregate shown is provided for operation in a verticalarrangement in which the axis of the housing middle part 13 extendsvertically. The lower screw 28 in this arrangement always dips into theoil internally. Via a blind hole therein, in the manner of communicatingtubes, a fluid connection exists between the interior of the housing 10and the display glass 27. The upper screw 28 is of exactly the same formas the lower screw 28, in order that, in the event of a changing fluidlevel, air can escape from the display glass 27 or flow into the displayglass. Because the web 25 is located at the center of a partial surface14, the display glass 27 lies flat with corresponding contact surfaceson the corresponding partial surface 14 of the housing middle part 13,without being unacceptably stressed. The housing middle part 13 has theinternal form of a circular regular cylinder between the webs 15 and 25.

At each end surface, the housing middle part 13 has a hollowed-outportion 32 extending from that end surface over a certain axial extentand reaching radially outward into the region of the circumferentialwall of the housing middle part 13, in the region of which the webs 15and 25 are thus fully hollowed-out. The housing cover 11 engages intoone recess 32 and the housing bottom 12 into the other hollowed-outportion, with one centering collar 33 in each case. Located in acircumferential channel of each centering collar 33 is a gasket 34, bymeans of which the gap is sealed relative to the housing parts. Thehousing cover, housing bottom and housing middle part are fixed to oneanother by radially driven flat-headed screws 35 in the region of thehollowed-out portions 32 and of the centering collars 33 which, as canbe seen from the conical apertures 36 in the circumferential wall of thehousing middle part 13 visible in FIG. 2, lie at the center of eachpartial surface 14.

The shaft 40 of the rotor of the electric motor 21 is mounted by meansof a bearing journal at each end in a rolling bearing, 41 and 42respectively, which is inserted into a seating of the housing cover 11or of the housing bottom 12. Just above the rolling bearing 42 in thehousing bottom 12, the shaft 40 bears a twist-proof centering ring 43toward which the radial pistons 44 of individual pump members 45 of aradial piston pump 46 fixed to the housing bottom 12 are urged by acompression spring 47. In the event of rotation of the shaft 40, theradial pistons 44 perform suction strokes during which pressure fluid isaspirated from the interior of the housing 10, and pressure strokes,during which they force the aspirated pressure fluid to a pressureoutlet (not shown in detail).

Located in the housing cover 11 is a filling aperture 51, which isclosed by a screw closure 52. In addition, the housing cover 11comprises a recess 53, initially open outward in the direction of theaxis 16 of the shaft 40, by which a connection box for the hydraulicaggregate is formed. The connection box 53 is covered by a plate 54 withthe interposition of a seal. A connection support produced from anelectrically insulating material is fixed on the bottom of theconnection box 53 and a plurality of connections are provided thereonfor the fixing and connecting of electrical lines. A bundle of linesleads through an aperture 55 in the bottom of the connection box 53 intothe interior of the housing 10 to the coils of the electric motor 21.Also provided in the bottom of the connection box 53 is a throughthreaded hole 56, into which a temperature sensor 57 is screwed from theinterior of the housing 10. The connecting lines of the temperaturesensor 57 lead directly through the threaded attachment of thetemperature sensor screwed into the threaded hole 56 into the connectionbox 53, but for which they would hang free in the interior of thehousing 10. A connecting cable for supplying the electric motor 21 canenter the connection box 53 through the screw connection 58.

Below the housing bottom 12 is disposed an oil cooler 65 with anelectrically driven fan wheel. The electric motor of the oil cooler isconnected to current via cable 64 which is guided from the electricmotor into the connection box 53. To prevent this cable 64, first, frombeing externally accessible on the hydraulic aggregate and thus capableof being damaged and making the handling of the hydraulic aggregate moredifficult, and secondly to prevent additional sealing points beingnecessary where the cable runs in the interior of the housing, a duct 66is provided in the wall of the housing middle part 13 which extends inthe axial direction along the housing middle part 13 and is guidedexternally past the gaskets 34. In order to sufficient housing materialto be available for a duct 66 that is continuous all round, an outwardcurvature 67 is provided on the housing middle part 13 in the region ofa corner between two partial surfaces 14. Attention is drawn to the factthat this outward curvature 67 is drawn at a different position in FIG.1 from that shown in FIG. 2, in order to enable it be shown in thesectional view according to FIG. 1. The outward curvature 67 iscontinued in the form of corresponding outward curvatures of the housingcover 11 and of the housing bottom 12, in order to enable the duct 66also to be extended into these parts. At the housing bottom, the duct 66opens directly and axially into the oil cooler 65. In the housing cover11, however, the duct 66 angles out of the axial direction into anoblique hole 68 which begins from a wall of the connection box 53. Promthe connection box 53, the cable 64 extends through the oblique hole 68and the longitudinal duct 66 to the oil cooler 65. It is thus protectedagainst any damage.

What is claimed is:
 1. A compact hydraulic aggregate having a housing(10) forming a reservoir for a pressure fluid and comprising a housingbottom (12), a housing cover (11) and a housing middle part (13)therebetween in form of a profiled tube, having, located in the housing(10), an electric motor (21) whose stator laminated core (19) is held bythe housing middle part (13), and which can be connected to anelectrical network via a connection box (53) on the housing cover (11),and having a pump (46) located within the housing (10) in a region ofthe housing bottom (12) and capable of being driven by the electricmotor (21), wherein the housing middle part (13) comprises axiallyextending holding webs (15) which are directed inwardly to engage atrespective positions the stator laminated core (19) of the electricmotor (21) to hold the stator core, and wherein there are plural sets ofthe holding webs located respectively at successive locations around thehousing, each set having a plurality of the webs.
 2. The compacthydraulic aggregate as claimed in claim 1, wherein the housing middlepart (13) has an external shape of a regular polygon.
 3. The compacthydraulic aggregate as claimed in claim 1, wherein an electricaltemperature sensor (57) is disposed in the housing cover (11) below aconnection box (53) and its electrical connecting lines lead from theconnecting box (53), through material of the housing cover (11),directly to the temperature sensor (57).
 4. The compact hydraulicaggregate as claimed in claim 3, wherein said temperature sensor (57) isdisposed in a hole (56) extending from the connection box (53).
 5. Thecompact hydraulic aggregate as claimed in claim 4, wherein the openingholding the temperature sensor (57) has screw threads permitting aninsertion of the temperature sensor from inside of the housing cover(11) into said hole (56) extending from the connection box (53), theelectrical connecting lines of the temperature sensor (57) also passingthrough said hole (56).
 6. The compact hydraulic aggregate as claimed inclaim 3, herein the temperature sensor is secured by screw threads inthe hole.
 7. A compact hydraulic aggregate having a housing (10) forminga reservoir for a pressure fluid and comprising a housing bottom (12), ahousing cover (11) and a housing middle part (13) therebetween in formof a profiled tube, having, located in the housing (10), an electricmotor (21) whose stator laminated core (19) is held by the housingmiddle part (13), and which can be connected to an electrical networkvia a connection box (53) on the housing cover (11), and having a pump(46) located within the housing (10) in a region of the housing bottom(12) and capable of being driven by the electric motor (21), wherein thehousing middle part (13) comprises axially extending holding webs (15)by which the stator laminated core (19) of the electric motor (21) isheld; and wherein the housing middle part (13) comprises a furtheraxially extending internal web (25) disposed in a first angular regionlocated between a first set of webs and a second successive set of websof said holding webs (15) and being broader in circumferential directionof the housing middle part (13) than the holding webs (15), the internalweb (25) serving to secure a monitoring member (27) disposed externallyon the housing (10).
 8. The compact hydraulic aggregate as claimed inclaim 7, herein said further internal web (25) extends radially inwardless than said holding webs (15).
 9. The compact hydraulic aggregate asclaimed in claim 8, wherein angular distance of said first angularregion is greater than the angular distance of a second angular regiondefined by third and fourth adjacent webs of said holding webs (15). 10.The compact hydraulic aggregate as claimed in claim 9, wherein a gap ofthe same size as a gap between the two holding webs (15) adjacent to thefurther web (25) exists opposite the further web (25) relative to anaxis (16) of the housing middle part (13).
 11. A compact hydraulicaggregate having a housing (10) forming a reservoir for a pressure fluidand comprising a housing bottom (12), a housing cover (11) and a housingmiddle part (13) therebetween in form of a profiled tube, having,located in the housing (10), an electric motor (21) whose statorlaminated core (19) is held by the housing middle part (13), and whichcan be connected to an electrical network via a connection box (53) onthe housing cover (11), and having a pump (46) located within thehousing (10) in a region of the housing bottom (12) and capable of beingdriven by the electric motor (21), wherein the housing middle part (13)comprises axially extending holding webs (15) by which the statorlaminated core (19) of the electric motor (21) is held; and furthercomprises an electrical device having a further electric motor and a fanwheel driven by the further electric motor, disposed in the region ofthe housing bottom (12), and wherein a supply cable (64) for theelectrical device is guided in an axially extending cable duct (66) ofthe housing middle part (13) to the housing cover (11).
 12. The compacthydraulic aggregate as claimed in claim 5, herein the housing middlepart (13) has a curvature (67) extending axially outward, within whichsaid cable duct (66) extends.
 13. The compact hydraulic aggregate asclaimed in claim 5, wherein the cable duct (66) is located radiallyoutside a seal (34) disposed between the housing middle part (13) andthe housing bottom (12) or the housing cover (11).
 14. The compacthydraulic aggregate as claimed in claim 11, wherein the cable duct (66)of the housing middle part (13) continues in holes (68, 69, 70) drilledin the housing cover (11) and the housing bottom (12).
 15. The compacthydraulic aggregate as claimed in claim 14, wherein the housing middlepart (13) is hollowed out inward from two ends and wherein the housingbottom (12) and housing cover (11) each engage by means of a centeringcollar (33) into a hollowed-out portion (32), wherein a radial seal (34)is disposed in the hollowed-out portion (32) between the housing middlepart (13) and the housing bottom (12) or the housing cover (11), andwherein the cable duct (66) extends outside the hollowed-out portion(32) in the housing middle part (13).
 16. The compact hydraulicaggregate as claimed in claim 11, wherein the electrical device is anoil cooler.
 17. A compact hydraulic aggregate having a housing (10)forming a reservoir for a pressure fluid and comprising a housing bottom(12), a housing cover (11) and a housing middle part (13) therebetweenin form of a profiled tube, having, located in the housing (10), anelectric motor (21) whose stator laminated core (19) is held by thehousing middle part (13), and which can be connected to an electricalnetwork via a connection box (53) on the housing cover (11), and havinga pump (46) located within the housing (10) in a region of the housingbottom (12) and capable of being driven by the electric motor (21),wherein the housing middle part (13) comprises axially extending holdingwebs (15) by which the stator laminated core (19) of the electric motor(21) is held; and wherein the holding webs are located in an arrangementbased on a regular polygon circumscribing the housing middle partwherein one of said holding webs (IS) extends at a center of eachexternal partial surface 114) of the polygon circumscribing the housingmiddle part (13) and lying between two corners of the polygon.
 18. Acompact hydraulic aggregate having a housing (10) forming a reservoirfor a pressure fluid and comprising a housing bottom (12), a housingcover (11) and a housing middle part (13) therebetween in form of aprofiled tube, having, located in the housing (10), an electric motor(21) whose stator laminated core (19) is held by the housing middle part(13), and which can be connected to an electrical network via aconnection box (53) on the housing cover (11), and having a pump (46)located within the housing (10) in a region of the housing bottom (12)and capable of being driven by the electric motor (21), wherein thehousing middle part (13) comprises axially extending holding webs (15)which are directed inwardly to engage at respective positions the statorlaminated core (19) of the electric motor (21) to hold the stator core,and wherein each of a plurality of the holding webs is provided with abearing shoulder (18) for receiving the stator core.